THe proposed research will be concerned with the structural requirements of narcotic antagonists. In the course of these studies, a number of piperidine, and pyrrolidine derivatives will be synthesized and tested for analgetic and narcotic antagonist activity. The structural features which will be investigated are: phenethylamine moiety, phenpropylamine moiety, and phenolic hydroxyl. The results of the pharmacological testing of the compounds will be used as guides in the selection of further analogs for synthesis and testing. The proposed studies will provide information which will assist in the design of agents to serve as economical replacements for naloxone in the prevention and treatment of narcotic addiction.